1 research outputs found
Influence of the Length and Charge on the Activity of α‑Helical Amphipathic Antimicrobial Peptides
Hydrophobic mismatch is important
for pore-forming amphipathic
antimicrobial peptides, as demonstrated recently [Grau-Campistany,
A., et al. (2015) <i>Sci. Rep.</i> <i>5</i>, 9388].
A series of different length peptides have been generated with the
heptameric repeat sequence KIAGKIA, called KIA peptides, and it was
found that only those helices sufficiently long to span the hydrophobic
thickness of the membrane could induce leakage in lipid vesicles;
there was also a clear length dependence of the antimicrobial and
hemolytic activities. For the original KIA sequences, the cationic
charge increased with peptide length. The goal of this work is to
examine whether the charge also has an effect on activity; hence,
we constructed two further series of peptides with a sequence similar
to those of the KIA peptides, but with a constant charge of +7 for
all lengths from 14 to 28 amino acids. For both of these new series,
a clear length dependence similar to that of KIA peptides was observed,
indicating that charge has only a minor influence. Both series also
showed a distinct threshold length for peptides to be active, which
correlates directly with the thickness of the membrane. Among the
longer peptides, the new series showed activities only slightly lower
than those of the original KIA peptides of the same length that had
a higher charge. Shorter peptides, in which Gly was replaced with
Lys, showed activities similar to those of KIA peptides of the same
length, but peptides in which Ile was replaced with Lys lost their
helicity and were less active